1. Field of the Invention
The present invention relates to a liquid discharge head for discharging liquid by creating a bubble (bubbles) with thermal energy acting upon liquid, and the method of manufacture therefor. The invention also relates to a liquid discharge apparatus that uses such liquid charge head.
Also, the present invention is applicable to a printer that records on a recording medium, such as paper, thread, fabric, cloth, leather, metal, plastic, glass, wood, ceramic, a copying machine, a facsimile equipments provided with communication system, and a word processor having a printing unit therefor. The invention further relates to an industrial recording apparatus formed complexly in combination with various processing apparatuses.
In this respect, the term “recording” referred to in the specification of the invention hereof not only means the provision of characters, graphics, and other meaningful images for a recording medium, but also, means the provision of images, such as patterns, which are not meaningful.
2. Related Background Art
Conventionally, for the so-called bubble jet recording method has been known, which is an ink jet recording method for forming images by the adhesion of ink onto a recording medium by discharging ink from discharge ports by the acting force based upon the abrupt voluminal changes following the creation of bubble by applying thermal energy or the like to liquid ink in flow paths of a recording apparatus, such as a printer. As disclosed in the specification of the U.S. Pat. No. 4,723,129, the recording apparatus that uses this bubble jet recording method is generally provided with discharge ports to discharge ink; flow paths communicated with these discharge ports; and electrothermal converting elements arranged in the flow paths to serve as energy generating means.
In accordance with a recording method of the kind, it becomes possible to record high quality images at high speeds in a lesser amount of noises, and at the same time, to arrange discharge ports for discharging ink in high density for the head using this recording method with such an excellent advantage, among some others, that recorded images are obtained in high resolution even in colors with a smaller apparatus. Therefore, the bubble jet recording method has been widely utilized for a printer, a copying machine, a facsimile equipment, and other office equipment in recent years. Further, this method has been utilized even for an industrial system, such as a textile printing apparatus.
Along with the wider utilization of bubble jet technologies and techniques for the products in various fields, there are increasingly more demands in various aspects. Then, for example, in order to obtain higher quality images, there has been proposed the driving condition whereby to provide a liquid discharge method or the like that performs excellent ink discharges at higher speeds based upon the stabilized creation of bubble or in consideration of the achievement of higher recording, there has been proposed the improved flow path configurations for obtaining a liquid discharge head having a higher refilling speed of liquid into the liquid flow path where liquid has been discharged.
Of these proposals, for the head that discharges liquid along with the growth and shrinkage of bubble created in nozzles, it has been known that the efficiency of discharge energy and the refilling characteristics of liquid tend to become unfavorably by the bubble growth in the direction opposite to the corresponding discharge port, and the resultant liquid flow caused thereby. The invention of a structure in which to enhance the discharge energy efficiency, as well as the refilling characteristics of the kind has been proposed in the specification of the European Patent Laid-Open Application EP-0436047A1.
The invention disclosed in the specification of this European Laid-Open Application is such that a first valve that cuts off the connection between the area near the discharge port and the bubble generating area, and a second valve that cuts off the connection between the bubble generating area and the ink supply portion completely, and that these valves are open and closed alternately (see FIG. 4 to FIG. 9 of the EP436047A1). For example, in accordance with the example shown in FIG. 7 of the aforesaid Laid-Open Application, a heat generating element 110 is arranged substantially in the center of the ink flow path 112 between the ink tank 116 and the nozzle 115 on the base plate 125 that forms the inner wall of the ink flow path 112 as shown in FIG. 37 hereof. The heat generating element 110 resides in the section 120 which closes all the circumferences in the interior of the ink flow path 112. The ink flow path 112 comprises the base plate 125; the thin films 123 and 126 which are laminated directly on the base plate 125; and tongue pieces 113 and 130 serving as closing devices. The tongue pieces in releasing condition are indicated by broken lines in FIG. 37. The other thin film 123 which extends on the flat plane parallel to the base plate 125 and terminates by the stopper 124 is arranged to shield over the ink flow path 112. When a bubble is created in ink, the free end of the tongue piece 130 on the nozzle region, which is in contact with the stopper 124 in its stationary condition, is displaced toward upward. Thus, ink liquid is discharged from the section 120 into the ink flow path 112, and discharged through the nozzle 115. At this juncture, the tongue piece 113, which is arranged in the area of the ink tank 116, is closely in contact with the stopper 124 in the stationary condition. Therefore, there is no possibility that ink liquid in the section 120 is directed to the ink layer 116. When the bubble in ink is extinct, the tongue piece 130 is displaced downward, and it is again closely in contact with the stopper 124. Then, the tongue piece 113 falls down in the ink section 120, thus allowing ink liquid to flow into the section 120.